[PATCH v4 3/7] drm/bridge: mhdp8546: Add minimal format negotiation

[Boris Brezillon]

On Tue, 1 Dec 2020 17:48:26 +0530
Nikhil Devshatwar <nikhil.nd at ti.com> wrote:

> With new connector model, mhdp bridge will not create the connector and
> SoC driver will rely on format negotiation to setup the encoder format.
> 
> Support minimal format negotiations hooks in the drm_bridge_funcs.
> Complete format negotiation can be added based on EDID data.
> This patch adds the minimal required support to avoid failure
> after moving to new connector model.
> 
> Signed-off-by: Nikhil Devshatwar <nikhil.nd at ti.com>
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen at ti.com>
> ---
> 
> Notes:
>     changes from v1:
>     * cosmetic fixes, commit message update
> 
>  .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 25 +++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> index d0c65610ebb5..2cd809eed827 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> @@ -2078,6 +2078,30 @@ cdns_mhdp_bridge_atomic_reset(struct drm_bridge *bridge)
>  	return &cdns_mhdp_state->base;
>  }
>  
> +static u32 *cdns_mhdp_get_input_bus_fmts(struct drm_bridge *bridge,
> +				      struct drm_bridge_state *bridge_state,
> +				      struct drm_crtc_state *crtc_state,
> +				      struct drm_connector_state *conn_state,
> +				      u32 output_fmt,
> +				      unsigned int *num_input_fmts)
> +{
> +	u32 *input_fmts;
> +	u32 default_bus_format = MEDIA_BUS_FMT_RGB121212_1X36;
> +
> +	*num_input_fmts = 0;
> +
> +	if (output_fmt != MEDIA_BUS_FMT_FIXED)
> +		return NULL;
> +
> +	input_fmts = kzalloc(sizeof(*input_fmts), GFP_KERNEL);
> +	if (!input_fmts)
> +		return NULL;
> +
> +	*num_input_fmts = 1;
> +	input_fmts[0] = default_bus_format;

Why not 

	input_fmts[0] = MEDIA_BUS_FMT_RGB121212_1X36;

?

This way you could get rid of the default_bus_format variable.

> +	return input_fmts;
> +}
> +
>  static int cdns_mhdp_atomic_check(struct drm_bridge *bridge,
>  				  struct drm_bridge_state *bridge_state,
>  				  struct drm_crtc_state *crtc_state,
> @@ -2142,6 +2166,7 @@ static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
>  	.atomic_duplicate_state = cdns_mhdp_bridge_atomic_duplicate_state,
>  	.atomic_destroy_state = cdns_mhdp_bridge_atomic_destroy_state,
>  	.atomic_reset = cdns_mhdp_bridge_atomic_reset,
> +	.atomic_get_input_bus_fmts = cdns_mhdp_get_input_bus_fmts,
>  	.detect = cdns_mhdp_bridge_detect,
>  	.get_edid = cdns_mhdp_bridge_get_edid,
>  	.hpd_enable = cdns_mhdp_bridge_hpd_enable,